Current commercial cylinders of high-pressure gases and high pressure volatile liquids are topped with valves which can be sheared off if the cylinder is dropped onto a hard surface such as a concrete slab, or through any other collision of the cylinder valve with a hard object. If the valve is sheared off, then the interior of the cylinder (which may be at a pressure of 2000 psi or higher) is suddenly opened to the atmosphere through an opening which may be 1/2" or more in diameter. The resultant burst of high-pressure gas produces a force which accelerates the cylinder and can turn it into a missile which can cause death or serious injury to persons in the vicinity, or major damage to buildings or equipment.
In order to lessen the likelihood that the valve will be sheared off, commercial cylinders are shipped with a metal cap covering the valve. The cap is supposed to be kept on whenever the cylinder is transported, or when it is stationary but not secured by chains or clamps. When the cylinder is in use, the cap must be removed in order to allow a regulator to be attached to the valve. It is also good practice to secure cylinders in use with chains or clamps to prevent them from falling with possible valve shear-off.
Although these practices generally are sufficient to prevent accidentally breaking off the valves, they are not infallible. Accidents could occur which would break off the valves in spite of these practices. Some use of gases supplied in high pressure cylinders, do not lend themselves to following these practices. For example, it is often difficult to secure a cylinder while the cylinder is used to supply gases for welding. Human error and failure to follow safe practices for the use and storage of high pressure cylinders is an even more prevalent cause for accidents resulting in shearing valves from high pressure cylinders.
It is desirable to eliminate the potential grave danger to personnel and equipment that exists when a gas cylinder valve is sheared off.
It is therefore an object of this invention to provide a pressure contained vessel which is not capable of propelling itself into the air in the event that valves or other fittings are severed from the vessel.